Specific Absorption Rate Mitigation

ABSTRACT

Specific Absorption Rate (SAR) mitigation techniques are described herein. In one or more embodiments, a host device is configured to implement a SAR mitigation algorithm to maintain compliance with regulatory requirements. The SAR mitigation algorithm may be configured to control radio frequency transmissions (e.g., output levels) for one or more antennas of the host device based at least in part upon an arrangement of an accessory device relative to the host device. By so doing, the SAR mitigation algorithm accounts for adverse influences that accessory devices may have upon radio frequency (RF) emissions from the antennas in some arrangements. The SAR mitigation algorithm may be further configured to account for user presence indications along with accessory device arrangements and adapt transmission power levels accordingly.

PRIORITY

This application is a divisional of and claims priority under 35 U.S.C.§121 to application Ser. No. 13/905,088 filed on May 29, 2013 and titled“Specific Absorption Rate Mitigation” the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND

Mobile computing devices have been developed to increase thefunctionality that is made available to users in a mobile setting. Forexample, a user may interact with a mobile phone, tablet computer, orother mobile computing device to check email, surf the web, composetexts, interact with applications, and so on. Modern mobile computingdevices may incorporate multiple antennas to support various wirelesssubsystems and communications. The multiple antennas may include forexample one or more Wi-Fi, Bluetooth, global navigation satellite system(GNSS), near field communication (NFC) and/or cellular antennas.

One challenge faced by mobile computing device designers is adherence toregulatory requirements that are imposed by entities such as the FederalCommunication Commission (FCC), the European Union (EU), and so forth.An example of such regulatory requirements is legal limits on SpecificAbsorption Rate (SAR) that are established in relation to radiofrequency (RF) energy associated with the various wireless andcommunications subsystems of a mobile computing device. A traditionalsolution for achieving compliance with SAR limits involves setting afixed maximum RF transmit power for communication hardware (e.g.,radios) to a power level that maintains legal compliance in the presenceof a user. However, placing such a fixed maximum on the transmit powerunderutilizes the capabilities of communication hardware and mayadversely affect communication connections and/or quality. Additionally,add-on hardware and/or accessory devices connectable to a host devicemay have adverse influences upon RF emissions of the host device thattypically are not accounted for in traditional mitigation approaches.Thus, traditional techniques for SAR compliance may be inadequate forsome device configurations and use scenarios.

SUMMARY

Specific Absorption Rate (SAR) mitigation techniques are describedherein. In one or more embodiments, a host device is configured toimplement a SAR mitigation algorithm to maintain compliance withregulatory requirements. The SAR mitigation algorithm may be configuredto control radio frequency transmissions (e.g., output levels) for oneor more antennas of the host device based at least in part upon anarrangement of an accessory device relative to the host device. By sodoing, the SAR mitigation algorithm accounts for adverse influences thataccessory devices may have upon radio frequency (RF) emissions from theantennas in some arrangements. The SAR mitigation algorithm may befurther configured to account for user presence indications along withaccessory device arrangements and adapt transmission power levelsaccordingly.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different instances in thedescription and the figures may indicate similar or identical items.Entities represented in the figures may be indicative of one or moreentities and thus reference may be made interchangeably to single orplural forms of the entities in the discussion.

FIG. 1 is an illustration of an environment in an example implementationthat is operable to employ the techniques described herein.

FIG. 2 depicts an example implementation of a computing device of FIG. 1in greater detail.

FIG. 3 depicts an example implementation of detectors for a host deviceto implement SAR mitigation techniques in dependence upon accessorydevice arrangement.

FIG. 4 depicts further example arrangements for detectors of a hostdevice to implement SAR mitigation techniques in dependence uponaccessory device arrangement.

FIG. 5 depicts illustrates some example rotational orientations of ahost device in relation to an accessory device.

FIG. 6 is a flow diagram that describes an example procedure in whichantennas are controlled in dependence upon a detected accessory devicearrangement.

FIG. 7 is a flow diagram that describes an example procedure in which aSAR mitigation algorithm is applied to selectively control antennas of ahost device.

FIG. 8 illustrates an example system including various components of anexample device that can be implemented as any type of computing deviceas described with reference to FIGS. 1-7 to implement techniquesdescribed herein.

DETAILED DESCRIPTION

Overview

One challenge faced by mobile computing device designers is adherence toSpecific Absorption Rate (SAR) limits that are established in relationto radio frequency (RF) emissions by mobile devices. A traditionalsolution involves setting a fixed maximum RF transmit power across allcommunication hardware, however, this approach generally sets acautiously low maximum to maintain compliance at the expense ofcommunication connection performance and/or quality.

Specific Absorption Rate (SAR) mitigation techniques are describedherein. In one or more embodiments, a host device is configured toimplement a SAR mitigation algorithm to maintain compliance withregulatory requirements. The SAR mitigation algorithm may be configuredto control radio frequency transmissions (e.g., output levels) for oneor more antennas of the host device based at least in part upon anarrangement of an accessory device relative to the host device. By sodoing, the SAR mitigation algorithm accounts for adverse influences thatsome arrangements of accessory devices may have upon radio frequency(RF) emissions from the antennas. The SAR mitigation algorithm may befurther configured to account for user presence indications along withaccessory device arrangement and adapt transmission power levelsaccordingly.

In the following discussion, an example environment and devices arefirst described that may employ the techniques described herein. Exampledetails and procedures are then described which may occur in the exampleenvironment and by the devices as well as in other environments and byother devices. Consequently, the example details and procedures are notlimited to the example environment/devices and the exampleenvironment/devices are not limited to performance of the exampledetails and procedures.

Example Operating Environment

FIG. 1 is an illustration of an environment 100 in an exampleimplementation that is operable to employ the techniques describedherein. The illustrated environment 100 includes an example of acomputing device 102 that is physically and communicatively coupled toan accessory device 104 via a flexible hinge 106. In this case thecomputing device 102 may be considered a host device to which one ormore accessory devices 104 are connectable in different arrangements.The computing device 102 may be configured in a variety of ways. Forexample, the computing device 102 may be configured for mobile use, suchas a mobile phone, a tablet computer as illustrated, and so on. Thus,the computing device 102 may range from full resource devices withsubstantial memory and processor resources to a low-resource device withlimited memory and/or processing resources. The computing device 102 mayalso relate to software that causes the computing device 102 to performone or more operations.

The computing device 102, for instance, is illustrated as including aninput/output module 108. The input/output module 108 is representativeof functionality relating to processing of inputs and rendering outputsof the computing device 102. A variety of different inputs may beprocessed by the input/output module 108, such as inputs relating tofunctions that correspond to keys of the input device, keys of a virtualkeyboard displayed by the display device 110 to identify gestures andcause operations to be performed that correspond to the gestures thatmay be recognized through the accessory device 104 and/or touchscreenfunctionality of the display device 110, and so forth. Thus, theinput/output module 108 may support a variety of different inputtechniques by recognizing and leveraging a division between types ofinputs including key presses, gestures, and so on.

In the illustrated example, the accessory device 104 is a deviceconfigured as a keyboard having a QWERTY arrangement of keys althoughother arrangements of keys are also contemplated. Further, othernon-conventional configurations for an accessory device 104 are alsocontemplated, such as a game controller, configuration to mimic amusical instrument, a power adapter, an accessory to provide wirelessfunctionality, and so forth. Thus, the accessory device 104 may assume avariety of different configurations to support a variety of differentfunctionality. Different accessory devices may be connected to thecomputing device at different times and in different arrangementsrelative to the computing device 102 (e.g., host device).

As previously described, the accessory device 104 is physically andcommunicatively coupled to the computing device 102 in this examplethrough use of a flexible hinge 106. The flexible hinge 106 representsone illustrative example of an interface that is suitable to connectand/or attach and accessory device to a computing device 102 acting as ahost. The flexible hinge 106 is flexible in that rotational movementsupported by the hinge is achieved through flexing (e.g., bending) ofthe material forming the hinge as opposed to mechanical rotation assupported by a pin, although that embodiment is also contemplated.Further, this flexible rotation may be configured to support movement inone direction (e.g., vertically in the figure) yet restrict movement inother directions, such as lateral movement of the accessory device 104in relation to the computing device 102. This may be used to supportconsistent alignment of the accessory device 104 in relation to thecomputing device 102, such as to align sensors used to change powerstates, application states, and so on.

The flexible hinge 106, for instance, may be formed using one or morelayers of fabric and include conductors formed as flexible traces tocommunicatively couple the accessory device 104 to the computing device102 and vice versa. This communication, for instance, may be used tocommunicate a result of a key press to the computing device 102, receivepower from the computing device, perform authentication, providesupplemental power to the computing device 102, and so on. The flexiblehinge 106 or other interface may be configured in a variety of ways tosupport multiple different accessory devices 104, further discussion ofwhich may be found in relation to the following figure.

As further illustrated in FIG. 1 the computing device 102 may includevarious applications 112 that provide different functionality to thedevice. A variety of applications 112 typically associated withcomputing devices are contemplated including, but not limited to, anoperating system, a productivity suite that integrates multiple officeproductivity modules, a web browser, games, a multi-media player, a wordprocessor, a spreadsheet program, a photo manager, and so forth.

The computing device 102 further includes one or more antennas 114 thatare representative of various antennas employed by the computing deviceto implement wireless functionality, subsystems, and communications. Inaccordance with techniques described herein, the antennas 114 mayinclude multiple different kinds of antennas (e.g., radios) that arearranged together within one or more antennas zones established for thecomputing device. In general, the antennas 114 may be placed to minimizeinterference between antennas and/or achieve performance objectives forthe suite of antennas as a whole. The placement of the antennas 114 mayalso minimize areas of the computing device 102 and/or accessory device104 which have restrictions that limit the materials and componentrythat may be placed with or near to the antenna suite 114. Areas withsuch restrictions may be referred to as radio frequency (RF) keep outs.A variety of different types of antennas, combinations of differenttypes of antennas, and arrangements of antennas are contemplated.

In accordance with SAR mitigation techniques described herein, thecomputing device 102 may be further configured to implement a SARmitigation algorithm to maintain compliance with regulatoryrequirements. As mentioned, the SAR mitigation algorithm may beconfigured to control transmission power levels for antennas 114 andthus RF emissions in dependence upon arrangement of the accessory devicerelative to the computing device, user presence indications, accessoryidentification data, and/or other factors considered individually or incombination. As shown in FIG. 1, the computing device may include a SARmanager module 116, one or more user presence detectors 118, and one ormore accessory detectors 120. The SAR manager module 116 representsfunctionality operable to implement a SAR mitigation algorithm and tocontrol antennas 114 to maintain SAR compliance in various scenarios.The SAR manager module 116 may be implemented as a standalone module, asfirmware of one or more antennas/communication subsystems, as acomponent of an operating system or other application 112 (e.g., anantenna performance and communication manager application), and soforth. To control antenna operations, the SAR manager module 116 may beconfigured to obtain user presence indications from user presencedetectors 118 and data indicative of an arrangement of the accessorydevice 104 from accessory detectors 120. SAR manager module 116 may alsoobtain and/or make use of accessory device identification data toidentify different accessories, determine properties of the accessorydevices, and distinguish between accessories. The user presencedetectors 118 and accessory detectors 120 are representative of suitablehardware, software, firmware, logic and combinations thereof to obtainuser presence indications and data indicative accessory devicearrangements, respectively, and to supply such information for use bythe SAR manager module 116. A variety of different physical sensors,sensor arrangements, and techniques for the user presence detectors 118and accessory detectors 120 may be employed, examples of which arediscussed in relation to the following figures.

To further illustrate, consider FIG. 2 which depicts generally at 200 anexample computing device 102 of FIG. 1 in greater detail. In thedepicted example, the computing device 102 is shown in a stand-aloneconfiguration without an accessory device 104 being attached. Inaddition to the components discussed in relation to FIG. 1, the examplecomputing device of FIG. 2 further includes a processing system 202 andcomputer-readable media 204 that are representative of various differenttypes and combinations of processing components, media, memory, andstorage components and/or devices that may be associated with acomputing device and employed to provide a wide range of devicefunctionality. In at least some embodiments, the processing system 202and computer-readable media 204 represent processing power andmemory/storage that may be employed for general purpose computingoperations. In the depicted example, the computer-readable media 204 isillustrated as storing the input/output module 108, application 112, andSAR manager module 116, which may be executed via the processing system202. More generally, the computing device 102 may be configured as anysuitable computing system and/or device that employ various processingsystems and computer-readable media to implement functionality describedherein, additional details and examples of which are discussed inrelation to the example computing system of FIG. 8.

The computing device 102 may also implement selected devicefunctionality through one or more microcontrollers 206. Themicrocontrollers 206 represent hardware devices/systems that aredesigned to perform a predefined set of designated tasks. Themicrocontrollers 206 may represent respective on-chip systems/circuitshaving self-contained resources such as processing components, I/Odevices/peripherals, various types of memory (ROM, RAM, Flash, EEPROM),programmable logic, and so forth. Different microcontrollers may beconfigured to provide different embedded applications/functionality thatare implemented at least partially in hardware and perform correspondingtasks. For example, the SAR manager module 116 may be implemented via amicrocontroller of the device in some implementations. Themicrocontrollers 206 enable performance of some tasks outside ofoperation of a general purpose processing system and otherapplications/components of the computing device or accessory device.Generally, power consumption of the microcontrollers is low incomparison with operating a general purpose processing system for adevice. Additionally, the microcontrollers 206 may enable wirelesscommunication systems of the device to remain on when the generalpurpose processing system is powered down and provide an always onalways connected (AOAC) feature.

As further depicted, a variety of different types of antennas 114 arecontemplated as represented in FIG. 2. By way of example, the antennas114 may include one or more Wi-Fi 208 antennas, global navigationsatellite system (GNSS) 210 antennas, cellular 212 antennas, Near FieldCommunication (NFC) 214 antennas, Bluetooth 216 antennas, and/or other218 antennas. In accordance with techniques described herein, theantennas 114 may include multiple antennas that may be interdependentupon one another and/or are arranged/designed in combination. In somescenarios, some wireless technologies may be implemented using two ormore individual radios/antennas.

For instance, the Wi-Fi 208 antennas may employ a two-by-two multipleinput/multiple output configuration (e.g., 2×2 MIMO). The Wi-Fi 208antennas may include at least a main and a MIMO antenna in someconfigurations. In addition, a Bluetooth 216 antenna may optionally becombined with the Wi-Fi 208 antennas. Further, modern cellulartechnologies such as Long Term Evolution (LTE), WiMax, and/or 4G mayemploy two or more cellular 212 antennas, such as a main cellularantenna and a MIMO cellular antenna and cover various frequencies,geographic areas, and so forth. The GNSS 210 antennas may be configuredfor use with various types of navigation standards, technologies, andsystems including but not limited to GPS, GLONASS, Galileo, and/orBeiDou navigation systems, to name some examples.

The computing device 102 of FIG. 2 also includes an example userpresence detector 118 and an example accessory detector 120. The userpresence detector 118 may be implemented in various ways. In thisexample, user presence detector 118 is configured as a hardware sensorcapable of detecting and indicating presence of a user relative to thecomputing device and/or relative to particular regions of the device forwhich SAR mitigation is relevant. For example, a user presence detector118 may be located proximate to antennas 114 to indicate when a user ispositioned in a manner relative to the antennas 114 that would increaseor decrease the likelihood of exceeding SAR limits. For instance,placing a hand over a region having one or more of the antennas 114 tohold a device may increase the amount of RF energy that the user isexposed to. On the other hand, some device hand positions for holding adevice may be at a sufficient distance from the antennas 114 to reduceexposure and permit higher RF energy outputs without causing SARviolations. Further, SAR compliance may depend in general upon whetheror not a user is physically interacting with the device and the contextof interaction.

Thus, if the device is set down to watch a media presentation or placedon a table after use, the level of potential exposure decreases. Useractions with a device such as typing, gestures, selecting buttons, andother types of input may be indicative of user presence. These and othercontextual factors regarding usage of the device may be considered alongwith information obtained directly from user presence detectors 118 todetermine when and how to adjust antenna output. By way of example, userpresence detectors 118 employed by a device may include but are notlimited to capacitive sensors, infrared radiation (IR) sensors, pressuresensors, optical detectors, a camera, and/or other type of sensorscapable of determining a relationship of a user relative to the deviceand supplying such information as user presence indications.

Likewise, the accessory detector 120 may be implemented in various ways.The accessory detectors 120 may be implemented as hardware sensorsplaced in various locations on a host device and/or on an accessorydevice itself. By way of example, accessory detectors 120 employed by adevice may include but are not limited to capacitive sensors, pressuresensors/switch, gyroscopes, accelerometers, optical detectors, magneticfield detectors, (e.g., hall effect sensors), mechanical switches,and/or other type of sensors that may be used individually or incombinations to determine arrangement of an accessory device relative toa host. As used herein, the arrangement of an accessory device mayinclude whether or not the accessory is connected to the host, alocation of the accessory, an orientation of the accessory relative thehost, an accessory identifier, and so forth.

In particular, one or more accessory detectors 120 may be included witha device to detect whether or not an accessory device is physicallyconnected to a host device. This may involve determining accessorydevice identification data using any suitable mechanism and/or accessorydetectors 120. For example, accessory device identification data may becommunicated via an interface (e.g., flexible hinge 106) that connectsand/or attaches an accessory device to a computing device 102. Theaccessory device identification data may be communicated when theaccessory is attached and may be stored by computing device 102 forreference and use by different modules/applications including the SARmitigation module 116. Attachment of the accessory may be recognizedusing one or more accessory detectors 120 associated with the interface.The accessory device identification data may be configured as analphanumeric code or string, a textual device name, a hardwareidentifier, or other suitable identifying data. The accessory deviceidentification data is sufficient to distinguish between differentaccessories and ascertain associated properties, characteristics, andcapabilities of the accessories that may be used to inform SARmitigation techniques as well as other operations.

Additionally, for accessory devices that may be manipulated intodifferent arrangements, the accessory detectors 120 may be configured todetect the different arrangements of accessory devices relative to ahost device to which the accessory devices are connected. In oneapproach, the accessory detectors 120 are placed upon one or moresurfaces of a host device and are operable to determine when anaccessory is positioned in a manner that causes interference withregions of the device in which antennas are housed. In somearrangements, the accessory may alter RF energy emissions in a mannerthat can direct more or less emissions toward a user. By recognizing thedifferent arrangements of accessory devices and understanding how theantenna emissions are changed in different arrangements, antennas may becontrolled in a manner that achieves compliance with SAR limits whileenabling AOAC features for communication systems and informedadjustments to antenna output under differing conditions that may boostperformance and quality of communications overall. Further detailsregarding example arrangements of accessory detectors 120 as well asuser presence detectors 118 are discussed in relation to the followingfigures.

Having discussed an example environment and devices, consider now someexample details regarding SAR mitigation techniques in accordance withvarious implementations.

SAR Mitigation Details

The following discussion presents some details regarding SAR mitigationtechniques and some illustrative examples. FIG. 3 depicts generally at300 one example implementation of detectors used to inform a SARmitigation algorithm. In particular, the computing device 102 isdepicted as including an antenna zone 302 having various antennas 114.Various combinations of antennas may be provided with a device. Asdepicted, the antenna zone 302 may be arranged along a selected edge ofthe computing device 102. In the illustrated example, the antenna zone302 extends substantially across a top edge of the device in a landscapeorientation. Other edges and/or multiple edges may also be selected someexamples of which are discussed in relation to the following figures.

A user presence detector 118 is also depicted in FIG. 3 as beingassociated with the antenna zone 302 and corresponding antennas 114.Generally, user presence detectors 118 may be placed within or proximateto an antenna zone 302 and/or in relation to individual antennas todetect when a user is “present.” The presence of a user in the contextof SAR mitigation refers to whether the relationship of the user to adevice encroaches upon the antenna zone 302 and corresponding antennas114 to an extent that potential for the user to be exposed to RFemissions above SAR limits is increased to an unacceptable level. A usermay be considered present under conditions that increase potentialexposure to unacceptable levels and considered not present when the useris sufficiently removed from the antenna zone 302 and correspondingantennas 114. Presence may be indicated for different antennas or groupsof antennas of a device on an individual basis. Thus a user may beconsidered present with respect to some antennas and at the same timeconsidered not present with respect to other antennas of a particulardevice.

User presence may be indicated for instance, when the user contactsareas of the device at or near to portions of the device that houseantennas (e.g., the antenna zone). Thus, if a user holds the examplecomputing device 102 of FIG. 3 along the top edge, the example one ormore user presence detectors 118 associated with the antenna zone 302may recognize this user interaction and generate an indication of userpresence for consumption by a SAR manager module 116. On the other hand,if a user places the computing device 102 down on a desk or table orholds the device at a different location, near the flexible hinge 106for example, the user is sufficiently removed from the antenna zone 302so that exceeding SAR limits becomes unlikely or impossible. In thiscase, the user may be considered not present with respect to therelationship of the user to antennas of the device and associated RFemissions. One or more user presence detectors 118 are provided torecognize the relationship of a user to RF emitting hardware componentsand to cause the SAR manager module 116 to take action to mitigateexposure under appropriate conditions.

FIG. 3 additionally depicts an example accessory detector 120 associatedwith the computing device 102. In this case, the example accessorydetector 120 may be a physical device that is placed in a location todetect when the accessory device is covering a surface of the computingdevice 102. For example, the arrow 304 indicates that the accessorydevice 104 may be manipulated via a flexible hinge 106 (or othersuitable interface) into different arrangements. In one arrangement, theaccessory device may be folded over into a closed position such that asurface 306 of the accessory device 104 covers a surface 308 of thecomputing device. In this arrangement, the accessory device 104 alsocovers the antenna zone 302 and antennas. Accordingly, the accessorydevice 104 may cause some interference and/or deflection of RF energyemitted by the antennas. Thus, the accessory detector 120 is positionedto detect arrangement of the accessory device into the closed positionand initiate actions by the SAR manager module 116 to mitigate exposure.One or more accessory detectors may be arranged at different locationsto recognize corresponding arrangements and initiate mitigation actionsfor SAR compliance as appropriate.

FIG. 4 depicts generally at 400 additional example arrangements ofdetectors that may be employed to inform a SAR mitigation algorithm.Generally, FIG. 4 represents that one or multiple user presencedetectors 118 may be employed in combination with one or multipleaccessory detectors 120 to implement SAR mitigation techniques describedherein. In particular, example placements and aspects of detectors thatmay be employed for the described SAR mitigation techniques areillustrated. In the depiction, the antenna zone 302 of FIG. 3 thatextends across top edge of the computing device 102 in a landscapeorientation is again included along with a corresponding user presencedetector 118. In addition or alternatively, the computing device 102 mayinclude one or more other antenna zones 402 examples of which are shownalong the short edges of the computing device in FIG. 4. As furthershown in FIG. 4, each of the antennas zones may include respectiveantennas and may be associated with one or more user presence detectors118 configured to determine user presence with respect to correspondingzones and antennas in the manner described above and below.

Further, the accessory device 104 of FIG. 4 is illustrated as includingarea 404 and areas 406 that correspond to antenna zone 302 and otherantennas zones 402, respectively. In particular, the area 404 and areas406 represent portions of the accessory device 104 that may interferewith antenna performance in some arrangements of the accessory device104 relative to a host computing device. For example, the area 404 andareas 406 may cover antenna zone 302 and other antennas zones 402 whenthe accessory device 104 is manipulated into a closed position asdiscussed in relation to FIG. 3. This may cause deflection of RF energyand/or other consequences that may adversely affect SAR complianceand/or performance. In some designs, non-interfering materials (e.g., RFtransparent plastic, paint, and so forth) may be selected for area 404and areas 406 to avoid such consequences. This approach though limitsthe types of materials available for accessories. The use of accessorydetectors 120 and a mitigation scheme as described herein enables designfreedom to use a wide range of materials and configurations foraccessories while achieving both acceptable communicationperformance/quality and SAR compliance.

Accordingly, one or multiple accessory detectors 120 may be employed todetermine arrangements of an accessory device 104 relative to acomputing device 102. As shown in FIG. 4, accessory detectors 120 may beassociated with one or more of the computing device 102, an interfaceused to communicatively and physically couple an accessory to a host(such as a flexible hinge 106), and/or the accessory device 104 itself.Multiple accessory detectors 120 may be used in combination to identifydifferent accessory devices, determine different arrangements ofaccessory devices, recognize when accessories areconnected/disconnected, determine where accessory devices are located,ascertain properties associated with different accessory devices, and soforth. Various information regarding accessory devices and arrangementsincluding but not limited to the preceding examples may be obtained atleast in part via accessory detectors 120 and used by the SAR managermodule 116 to selectively adjust antenna operation in dependence onaccessory device arrangements and properties to balance performance andSAR compliance in different circumstances.

FIG. 5 illustrates generally at 500 an example in which a computingdevice 102 may be rotated within a variety of different angle rangeswith respect to an accessory device 104 that correspond to differentarrangements. Generally, different arrangements of an accessory device104 relative to a computing device 102 may occur at different times. Theaccessory device 104 may also be removably connectable to the computingdevice 102 via a flexible hinge 106 or other suitable interface. Indifferent arrangements, the different antennas and/or antenna zones maybecome more or less effective for various kinds of wirelesscommunication. For example, different zones may become blocked andunblocked as the accessory is manipulated into different arrangements.

Different arrangements can be associated with different power states,different application states, use of different wirelessantennas/antennas zones, and so on. Additionally, the differentarrangements and/or select pre-defined arrangements may be recognizedand used to inform a SAR mitigation algorithm implemented by the SARmanager module 116. Naturally, different accessories may have differentcharacteristics and capabilities including different kinds ofarrangements that may occur relative to a host. Techniques for SARmitigation discussed herein are generally applicable to variousdifferent arrangements associated with different accessories and are notlimited to the illustrative examples discussed above and below.

In the example of FIG. 5 an angle range 502 is illustrated, whichcorresponds to a closed position in which a front surface (e.g., inputside or key side of a keyboard accessory) of the accessory device 104may cover a front surface (e.g., display side) of the computing device102. The closed position may be detected via accessory detectors 120 asdiscussed herein or in another suitable way. Thus, if the computingdevice 102 is positioned at an angle within the angle range 502 relativeto the accessory device 104, the computing device 102 can be determinedto be in a closed position. A closed position can include an associatedclosed state where various functionalities/behaviors for the computingdevice 102 and accessory device 104 including antenna operations can bemodified accordingly based on the closed state. This may includeswitching between different antenna zones, selectively turning antennason/off, selecting various wireless functionality provided by one or moreantennas 114, modifying power output for SAR compliance and/or toimprove performance, and so forth. Within the angle range 502 forinstance, the accessory may cause interference with antenna operation.In this case, the SAR manager module 116 may be configured to recognizethat the accessory device 104 is positioned in an arrangement thatadversely affects SAR compliance and may take action to control antennasfor SAR compliance accordingly. For instance, RF transmit power may bereduced for one or more antennas to maintain SAR compliance.

Further illustrated is an angle range 504, which may correspond to atyping arrangement for the computing device 102. Thus, if the computingdevice 102 is positioned at an angle within the angle range 504 relativeto the accessory device 104, the computing device 102 can be determinedto be in a typing arrangement. Within this orientation, the computingdevice 102 and/or the accessory device 104 can be placed in a typingpower state where functionalities/behaviors for the computing device 102and accessory device 104 including antenna operations can be customizedaccordingly based on the typing state.

Additionally, FIG. 5 illustrates an angle range 506, which correspondsto a viewing arrangement for the computing device 102. Thus, if thecomputing device 102 is positioned at an angle within the angle range506 relative to the accessory device 104, the computing device 102 canbe determined to be in a viewing arrangement. In this orientation,functionalities/behaviors for the computing device 102 and accessorydevice 104 including antenna operations can be controlled accordinglybased on the viewing state.

Generally, within the angle ranges 504 and 506, interference withantenna operation by the accessory device 104 may be minimal. In thiscase, the SAR manager module 116 may be configured to recognize that theaccessory device 104 is positioned in an arrangement that does notadversely affect SAR compliance and may take action to control antennasfor performance accordingly. For instance, RF transmit power may beboosted for performance when the arrangement of an accessory to a hostis in the angle ranges 504 and 506 shown in FIG. 5.

An angle range 508 is also illustrated in which the computing device 102and accessory device 104 are manipulated one to another such that abackside of the computing device 102 (e.g., side opposite the displayside) is folded around into relatively close proximity and/or contactwith a backside of the accessory 104. This arrangement corresponds toanother closed position in which a back surface (e.g., side opposite theinput side) of the accessory device 104 may cover a back surface (e.g.,side opposite of display side) of the computing device 102. Thus, if thecomputing device 102 is positioned at an angle within the angle range508 relative to the accessory device 104, the computing device 102 canagain be determined to be in a closed position. Accordingly, the SARmanager module 116 may recognize that the accessory device 104 ispositioned in an arrangement that adversely affects SAR compliance andmay take action to control antennas for SAR compliance accordingly.

Having discussed some example SAR mitigation details, consider exampleprocedures in accordance with one or more implementations.

Example Procedures

The following discussion describes SAR mitigation techniques that may beimplemented utilizing the previously described systems and devices.Aspects of each of the procedures may be implemented in hardware,firmware, software, or a combination thereof. The procedures are shownas a set of blocks that specify operations performed by one or moredevices and are not necessarily limited to the orders shown forperforming the operations by the respective blocks.

FIG. 6 depicts an example procedure 600 in which antennas for a hostdevice are controlled in dependence upon arrangement of an accessorydevice. An arrangement of an accessory device relative to a hostcomputing device to which the accessory device is physically connectableis detected (block 602). For example, one or more accessory sensors 120may be employed to recognize an arrangement of an accessory aspreviously discussed. An arrangement may encompass the location ofconnection and/or an orientation for an accessory device relative to thehost computing device. As described above and below, additionalinformation such as an accessory identity and/or user presenceindications may also be employed along with a detected accessoryarrangement to determine when and how to implement SAR mitigationactions. A variety of different arrangements are contemplated at leastsome of which may negatively impact SAR compliance if mitigation actionsare not taken. Thus, detection of such arrangements may trigger controlactions to adapt antenna operation for compliance. On the other handsome arrangements have no substantial impact on SAR compliance in whichcase antennas may be controlled to optimize performance. Accordingly,antenna operation may be modified in various ways based upon anarrangement of an accessory device that is detected.

In particular, a transmission power level is set for one or moreantennas of the host computing device in dependence upon the detectedarrangement (block 604). For example, the SAR manager module 116 may beoperable to recognize particular arrangements of different accessoriesbased on information obtained via the accessory sensors 120. The SARmanager module 116 may then modify transmission power levels and/orother operational parameters for one or more antennas 114 of a hostdevice accordingly. This may include, reducing transmission power levelsfor SAR compliance in response to detection of some arrangements andboosting transmission power levels for performance in response todetection of some other arrangements. Moreover, different antennas maybe controlled individually based on the accessory arrangement such thatfor a given arrangement one or more selected antennas having thepotential to cause excessive SAR conditions may be controlled forcompliance (e.g., reduce energy output/power level) while in the samearrangement other antennas (e.g., antennas that do not contribute toexcess SAR conditions) may continue to operate “normally” and/or may beboosted for performance. In at least some embodiments, a maximumtransmission power level for may be established for each antenna withrespect to different arrangements of a particular accessory device andindividually with respect to different accessory device. Accordingly,setting of transmission power levels may involve enforcing a maximumtransmission power level for each antenna established with respect to adetected arrangement an accessory device.

In order to selectively control antennas in dependence on accessoryarrangement, the SAR manager module 116 may include or otherwise makeuse of any suitable information that associates particular arrangementsof different accessories with operational parameters for one or moreantennas 114. For example, the SAR manager module 116 may reference atable, database, data file, library, or other data structure that mapstransmission power level ranges/maximums for individual antennas todifferent accessory arrangements in order to determine transmissionpower levels to set for a detected arrangement. The mapping datastructure may be defined to associate antenna operational parametersand/or corresponding control actions with accessory arrangements foreach different accessory based on accessory identification data. Thus,given an accessory device identity and information regarding a currentarrangement, the SAR manager module 116 may look-up correspondingantenna operational parameters and selectively control antennas 114accordingly. For example, the SAR manager module 116 may apply a SARmitigation algorithm to control antennas 114 further details of whichare described in relation to the following figure.

FIG. 7 depicts an example procedure 700 in which a specific absorptionrate (SAR) mitigation algorithm is applied to control one or moreantennas of a host computing device. A SAR mitigation algorithm for ahost computing device is instantiated that is dependent upon a userpresence indication and arrangement of an accessory device connectableto the host device relative to the host device (block 702). For example,the SAR mitigation may be implemented and applied by a SAR managermodule to effectuate techniques for SAR mitigation described herein.Generally speaking, the SAR mitigation algorithm is configured toindicate control actions to take with respect to one or more antennas inrelation to different conditions. The conditions may include at leastwhether or not a user is present with respect to individual antennasand/or a current arrangement of an accessory device relative to a host.As noted, an identity of the accessory device is another condition thatmay be obtained and used in conjunction with the detectedarrangement/user presence indications to ascertain how and when tocontrol antenna operations for SAR mitigation and/or performance.

For instance, the identity may be indicative of accessory deviceproperties at least some of which may impact SAR compliance. Forinstance, properties including but not limited to accessory type,location of connections, materials of construction, hardware aspects,emission contributions, and so forth may be associated with identitiesof different accessories. Given an accessory device identity andcorresponding properties, effects of the accessory device on SARcompliance in different arrangements may be determined. A SAR mitigationalgorithm may then be defined accordingly. In at least someimplementations, the SAR mitigation algorithm may be configured toinclude a mapping data structure as mentioned above that associatesvarious conditions (e.g., user presence, accessory identification,and/or accessory arrangement) with various antenna control actions.

An indication of user presence is ascertained (block 704). User presencemay be detected via one or more user presence detectors 118 in themanner previously described. As noted, the presence of the user isdetermined with respect to proximity of the user to individual antennas.Thus, a user may be present with respect to some antennas of a device(e.g., hand holding device at or near to an antenna location) and at thesame time the user may be considered not present with respect to otherantennas located in a different part of the device.

Arrangement of the accessory device is detected (block 706). Again, oneor more accessory sensors 120 may be employed to recognize anarrangement of an accessory using the techniques described herein. Then,the SAR mitigation algorithm is applied to control radio frequencytransmissions for one or more antennas of the host device according theascertained user presence indication and the detected arrangement of theaccessory device (block 708). The operation of one or more antennas 114may be controlled in various ways. In general, the SAR mitigationalgorithm is configured to implement a control scheme that accounts forconditions including but not limited to user presence, accessoryidentity, and/or accessory arrangement as discussed above. The SARmitigation algorithm is further designed to maintain compliance with SARlimits while permitting always on always connected (AOAC) features forwireless communication systems in the presence of different accessorydevice.

By way of example and not limitation, antenna control actions designatedby the SAR mitigation algorithm may include but are not limited tosetting transmission power limits, throttling of one or more antennas ortypes of antennas, prioritization of antenna communications, powerback-off adjustments, as well as intentional radio degradation and/orradiation pattern modifications achieved through programmable elements(e.g., counter-measure devices), to name a few examples. One or morecontrol actions to mitigate potential for exceeding legal SAR limits maybe applied for antennas that contribute to SAR emissions. On the otherhand, control actions to boost or maintain performance may be appliedfor antennas that do not significantly contribute to SAR emissionsbecause of antenna location, user presence relationships, and, accessorydevice arrangement. Generally antennas that contribute and do notcontribute to potential excessive SAR emissions may be identified basedon user presence indications for individual antennas and the accessoryarrangement. The antennas identified as contributor and non-contributorto SAR emissions for a given scenario may then be controlled on anindividual basis for compliance considerations and performanceconsiderations, respectively.

Naturally, control actions may be intelligently implemented based uponthe current state of antenna operations rather than by simply settingoverly cautious maximums or applying fixed back-off percentages orvalues. For example, power may be reduced for an antenna in response touser presence/accessory arrangement detection when the transmit power isabove a defined threshold to trigger mitigation. On the other hand, thepower may not be reduced when transmit power is below the definedthreshold even though the user is present and a particular accessoryarrangement is detected. The reduction may therefore depend upon thecurrent operational conditions of an antenna. Moreover, differentantennas may be controlled differently based on location, type ofantenna, priority, user presence, and other contextual conditions ratherthan applying blanket across the board adjustments to each antenna.

In accordance with the foregoing description, a SAR mitigation algorithmmay be implemented to control radio frequency transmissions (e.g.,output levels) for one or more antennas of the host device based atleast in part upon an arrangement of an accessory device relative to thehost device. By so doing, the SAR mitigation algorithm accounts foradverse influences that some arrangements of accessory devices may haveupon radio frequency (RF) emissions from the antennas. The SARmitigation algorithm may be further configured to account for userpresence indications along with accessory device arrangement andaccessory device identity to adapt transmission power levelsaccordingly.

Having considered the foregoing example procedures, consider now adiscussion of example systems and devices that may be employed toimplement aspects of techniques in one or more embodiments.

Example System and Device

FIG. 8 illustrates an example system generally at 800 that includes anexample computing device 802 that is representative of one or morecomputing systems and/or devices that may implement the varioustechniques described herein. The computing device 802 may, for example,be configured to assume a mobile configuration through use of a housingformed and size to be grasped and carried by one or more hands of auser, illustrated examples of which include a mobile phone, mobile gameand music device, and tablet computer although other examples are alsocontemplated.

The example computing device 802 as illustrated includes a processingsystem 804, one or more computer-readable media 806, and one or more I/Ointerface 808 that are communicatively coupled, one to another. Althoughnot shown, the computing device 802 may further include a system bus orother data and command transfer system that couples the variouscomponents, one to another. A system bus can include any one orcombination of different bus structures, such as a memory bus or memorycontroller, a peripheral bus, a universal serial bus, and/or a processoror local bus that utilizes any of a variety of bus architectures. Avariety of other examples are also contemplated, such as control anddata lines.

The processing system 804 is representative of functionality to performone or more operations using hardware. Accordingly, the processingsystem 804 is illustrated as including hardware elements 810 that may beconfigured as processors, functional blocks, and so forth. This mayinclude implementation in hardware as an application specific integratedcircuit or other logic device formed using one or more semiconductors.The hardware elements 810 are not limited by the materials from whichthey are formed or the processing mechanisms employed therein. Forexample, processors may be comprised of semiconductor(s) and/ortransistors (e.g., electronic integrated circuits (ICs)). In such acontext, processor-executable instructions may beelectronically-executable instructions.

The computer-readable media 806 is illustrated as includingmemory/storage 812. The memory/storage 812 represents memory/storagecapacity associated with one or more computer-readable media. Thememory/storage component 812 may include volatile media (such as randomaccess memory (RAM)) and/or nonvolatile media (such as read only memory(ROM), Flash memory, optical disks, magnetic disks, and so forth). Thememory/storage component 812 may include fixed media (e.g., RAM, ROM, afixed hard drive, and so on) as well as removable media (e.g., Flashmemory, a removable hard drive, an optical disc, and so forth). Thecomputer-readable media 806 may be configured in a variety of other waysas further described below.

Input/output interface(s) 808 are representative of functionality toallow a user to enter commands and information to computing device 802,and also allow information to be presented to the user and/or othercomponents or devices using various input/output devices. Examples ofinput devices include a keyboard, a cursor control device (e.g., amouse), a microphone, a scanner, touch functionality (e.g., capacitiveor other sensors that are configured to detect physical touch), a camera(e.g., which may employ visible or non-visible wavelengths such asinfrared frequencies to recognize movement as gestures that do notinvolve touch), and so forth. Examples of output devices include adisplay device (e.g., a monitor or projector), speakers, a printer, anetwork card, tactile-response device, and so forth. Thus, the computingdevice 802 may be configured in a variety of ways to support userinteraction.

The computing device 802 is further illustrated as being communicativelyand physically coupled to an accessory device 814 that is physically andcommunicatively removable from the computing device 802. In this way, avariety of different accessory devices may be coupled to the computingdevice 802 having a wide variety of configurations to support a widevariety of functionality. In this example, the accessory device 814includes one or more controls 816, which may be configured aspress-sensitive keys, mechanically switched keys, buttons, and so forth.

The accessory device 814 is further illustrated as including one or moremodules 818 that may be configured to support a variety offunctionality. The one or more modules 818, for instance, may beconfigured to process analog and/or digital signals received from thecontrols 816 to determine whether an input was intended, determinewhether an input is indicative of resting pressure, supportauthentication of the accessory device 814 for operation with thecomputing device 802, and so on.

Various techniques may be described herein in the general context ofsoftware, hardware elements, or program modules. Generally, such modulesinclude routines, programs, objects, elements, components, datastructures, and so forth that perform particular tasks or implementparticular abstract data types. The terms “module,” “functionality,” and“component” as used herein generally represent software, firmware,hardware, or a combination thereof. The features of the techniquesdescribed herein are platform-independent, meaning that the techniquesmay be implemented on a variety of commercial computing platforms havinga variety of processors.

An implementation of the described modules and techniques may be storedon or transmitted across some form of computer-readable media. Thecomputer-readable media may include a variety of media that may beaccessed by the computing device 802. By way of example, and notlimitation, computer-readable media may include “computer-readablestorage media” and “computer-readable signal media.”

“Computer-readable storage media” may refer to media and/or devices thatenable storage of information in contrast to mere signal transmission,carrier waves, or signals per se. Thus, computer-readable storage mediadoes not include signal bearing media or signals per se. Thecomputer-readable storage media includes hardware such as volatile andnon-volatile, removable and non-removable media and/or storage devicesimplemented in a method or technology suitable for storage ofinformation such as computer readable instructions, data structures,program modules, logic elements/circuits, or other data. Examples ofcomputer-readable storage media may include, but are not limited to,RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM,digital versatile disks (DVD) or other optical storage, hard disks,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, or other storage device, tangible media, orarticle of manufacture suitable to store the desired information andwhich may be accessed by a computer.

“Computer-readable signal media” may refer to a signal-bearing mediumthat is configured to transmit instructions to the hardware of thecomputing device 802, such as via a network. Signal media typically mayembody computer readable instructions, data structures, program modules,or other data in a modulated data signal, such as carrier waves, datasignals, or other transport mechanism. Signal media also include anyinformation delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media include wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared, and other wireless media.

As previously described, hardware elements 810 and computer-readablemedia 806 are representative of modules, programmable device logicand/or fixed device logic implemented in a hardware form that may beemployed in some embodiments to implement at least some aspects of thetechniques described herein, such as to perform one or moreinstructions. Hardware may include components of an integrated circuitor on-chip system, microcontroller devices, an application-specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), acomplex programmable logic device (CPLD), and other implementations insilicon or other hardware. In this context, hardware may operate as aprocessing device that performs program tasks defined by instructionsand/or logic embodied by the hardware as well as a hardware utilized tostore instructions for execution, e.g., the computer-readable mediadescribed previously.

Combinations of the foregoing may also be employed to implement varioustechniques described herein. Accordingly, software, hardware, orexecutable modules may be implemented as one or more instructions and/orlogic embodied on some form of computer-readable media and/or by one ormore hardware elements 810. The computing device 802 may be configuredto implement particular instructions and/or functions corresponding tothe software and/or hardware modules. Accordingly, implementation of amodule that is executable by the computing device 802 as software may beachieved at least partially in hardware, e.g., through use ofcomputer-readable media and/or hardware elements 810 of the processingsystem 804. The instructions and/or functions may be executable/operableby one or more articles of manufacture (for example, one or morecomputing devices 802 and/or processing systems 804) to implementtechniques, modules, and examples described herein.

CONCLUSION

Although the example implementations have been described in languagespecific to structural features and/or methodological acts, it is to beunderstood that the implementations defined in the appended claims isnot necessarily limited to the specific features or acts described.Rather, the specific features and acts are disclosed as example forms ofimplementing the claimed features.

What is claimed is:
 1. A method comprising: detecting an arrangement ofan accessory device relative to a host computing device to which theaccessory device is physically connectable; and setting transmissionpower levels for one or more antennas of the host computing device independence upon the detected arrangement of the accessory device.
 2. Amethod as described in claim 1, wherein setting the transmission powerlevels comprises reducing a transmission power level of at least one ofsaid antennas in dependence upon the detected arrangement to maintaincompliance with a legal limit established for specific absorption rate(SAR).
 3. A method as described in claim 1, wherein setting thetransmission power levels comprises enforcing a maximum transmissionpower level for each of the one or more antennas established withrespect to the detected arrangement of the accessory device.
 4. A methodas described in claim 1, setting the transmission power levelscomprises: obtaining accessory identification data indicative of anidentity of the accessory device; looking-up antenna operationalparameters for the one or more antennas based upon the detectedarrangement and the identity of the accessory device; and setting thetransmission power levels in accordance with the antenna operationalparameters.
 5. A method as described in claim 1, wherein the accessorydevice is removably connectable communicatively and physically to thehost computing device via an interface.
 6. A method as described inclaim 5, wherein the interface in configured to enable manipulation ofthe accessory device relative to the host computing device into multipledifferent arrangements, the multiple different arrangements eachassociated with respective operational parameters for the one or moreantennas.
 7. A method as described in claim 1, wherein detecting thearrangement comprises recognizing the arrangement from multiple possiblearrangements via one or more accessory detectors provided with the hostcomputing device.
 8. A method as described in claim 7, wherein theaccessory detectors comprise one or more of a capacitive sensor, apressure sensor, a gyroscope, an accelerometer, an optical detector, ora magnetic field detector.
 9. A method as described in claim 1, whereinthe one or more antennas include at least a pair of cellular antennasfor cellular communications.
 10. A computing device comprising: one ormore antennas configured to provide wireless communicationfunctionality; one or more hardware elements configured to implement aspecific absorption rate manager module operable to: obtain accessoryidentification data indicative of an identity of an accessory devicecommunicatively and physically coupled to the host computing device viathe interface; detect an arrangement of the accessory device relative tothe host computing device; identify antenna control actions indicatedfor the one or more antennas with respect to the detected arrangementand the identity of the accessory device; and control operations of theone or more antennas in accordance with the identified antenna controlactions.
 11. The computing device as described in claim 10, wherein theantenna control actions comprise one or more of setting transmissionpower limits, throttling of one or more antennas, prioritization ofantenna communications, power back-off adjustments, intentional radiodegradation, or radiation pattern modifications.
 12. The computingdevice as described in claim 10, wherein control of the operationsincludes applying control actions to mitigate potential for exceedinglegal specific absorption rate (SAR) limits be applied for antennas thatcontribute to SAR emissions in relation to the detected arrangement. 13.The computing device described in claim 10, wherein control of theoperations includes applying control actions to boost or maintainperformance for antennas that do not significantly contribute to SARemissions in relation to the detected arrangement.
 14. The computingdevice described in claim 10, wherein identification of the antennacontrol actions comprises referencing a mapping data structure tolook-up control actions associated with the one or more antennas inrelation to the detected arrangement and the identity of the accessorydevice, the mapping data structure configured to associate antennaoperational parameters and corresponding control actions with accessorydevice arrangements for multiple different accessory devices connectableto the host computing device at different times via the interface. 15.The computing device described in claim 10, wherein the antennas includeat least a pair of cellular antennas to provide cellular communications,a pair of Wi-Fi antennas for Wi-Fi communications, and a globalnavigation satellite system (GNSS) antenna to provide global navigation.16. A host computing device comprising: a processing system; aninterface to communicatively and physically couple different accessorydevices to the host computing device; multiple antennas to providewireless communication functionality; one or more computer readablemedia comprising instructions that, when executed via the processingsystem, implement a specific absorption rate (SAR) mitigation algorithmconfigured to perform operations to control operations of the multipleantennas comprising: obtaining accessory identification data indicativeof an identity of an accessory device communicatively and physicallycoupled to the host computing device via the interface; detecting anarrangement of the accessory device relative to the host computingdevice; identifying antenna control actions indicated for the one ormore antennas with respect to the detected arrangement and the identityof the accessory device; and controlling operations of the one or moreantennas in accordance with the identified antenna control actions. 17.The host computing device as recited in claim 16, wherein the antennacontrol actions comprise one or more of setting transmission powerlimits, throttling of one or more antennas, prioritization of antennacommunications, power back-off adjustments, intentional radiodegradation, or radiation pattern modifications.
 18. The host computingdevice as recited in claim 16, wherein controlling operations of the oneor more antennas in accordance with the identified antenna controlactions comprises: applying control actions to mitigate potential forexceeding legal specific absorption rate (SAR) limits be applied forantennas that contribute to SAR emissions in relation to the detectedarrangement; and applying control actions to boost or maintainperformance for antennas that do not significantly contribute to SARemissions in relation to the detected arrangement.
 19. A host computingdevice recited in claim 16, wherein identifying the antenna controlactions comprises referencing a mapping data structure to look-upcontrol actions associated with the one or more antennas in relation tothe detected arrangement and the identity of the accessory device, themapping data structure configured to associate antenna operationalparameters and corresponding control actions with accessory devicearrangements for multiple different accessory devices connectable to thehost computing device at different times via the interface.
 20. The hostcomputing device as recited in claim 16, wherein the antennas include atleast a pair of cellular antennas to provide cellular communications, apair of Wi-Fi antennas for Wi-Fi communications, and a global navigationsatellite system (GNSS) antenna to provide global navigation.